Rock Creek Lake IA 03-NSK-865

Assessment Comments

Assessment is based on results of water quality monitoring and information from the DNR Fisheries Bureau. See attached document.

Basis for Assessment

Both swimmable and fishable uses were assessed as PS for the 1994 report for the following reasons:  (1) BPJ of DNR field staff and Fisheries agree than the lake is impaired by agricultural NPS runoff, but both tend to assess the lake as NS; (2) results of monitoring in 1990 show that average levels of secchi depth and total-P are worse than overall averages for the 116 SPOLs sampled in 1990 and 1992, but they are well within the overall average +/- 1 SD; levels of chl-a and TSS are at or better than the overall averages; (3) according to Bachmann et al.  (1994), lake has a relatively low sedimentation rate (1.8 cm/yr) and relatively long life expectancy (144 years); they also report relatively high use figures for fishing and swimming.   Thus, although WQ problems exist at the lake, WQ is close to average, and the lake continues to support both fishing and swimming.